WWII MISTERIES: What happened with the JU390?

[Soren]

Compare the above to the power available to the B29 at that altitude and you'll quickly realize why there was such a big difference in service ceiling.

[drgondog]

Originally Posted by Soren

Listen are you guys interested about knowing the truth or do you just want to argue ??

Interesting question Soren - what is the 'truth' - your truth or the sketchy details provided by other equally vague sources?

uboat.net - Technical pages - Junkers Ju 290 and Ju 390

The Ju-390
Two prototypes flew of a radically modified derivative, the Ju 390. The idea behind this was simple: The wing center section panels, complete with engines and landing gear, where fitted twice. The fuselage was elongated. In this was the four-engine Ju 290 was modified into the six-engine Ju 390. The Ju 390V1 was equipped as as a transport aircraft, and the Ju 390V2 as a long-distance maritime patrol aircraft.
They flew in August and October of 1943. The V2 was delivered to FAGr.5, and it demonstrated its potential by flying from Mont-de-Marsan to a point 20km from New York, and back. [Editor: many believe this is a rumor and that the flight was never undertaken]



Specifications
Junkers Ju 290A-5
Nine-seat long-distance reconnaissance aircraft

Four 1700hp BMW 801D radial engines Wing span 42.00m, length 28.64m, height 6.83m, wing area 203.6m2. Maximal take-off weight 44970kg. Max. speed 440km/h at 5800m, cruising speed 360km/h. Service ceiling 6000m Range 6150km

Armament: Two dorsal turrets, each with a 15mm MG151, one MG151 in the tail, two in beam windows, and one in the front of the under nose gondola. One 13mm MG131 in the aft section of the gondola.



Specifications
Junkers Ju 390V2

Six 1970hp BMW 801E radial engines Wing span 50.32m, length 33.6m Empty weight 36900kg, max. take-off weight 53112kg Max. speed 515km/h at 6200m, cruising speed 357km/h. Max. range 9700km.

Armament: Two dorsal gun turrets, each with a MG151, and one MG 151 in the tail. Aft and front MG131s in the gondola, and two MG131 beam guns.


For the last time the Ju-390 was equipped with the BMW-801 D-2 series NOT the E series!

And here's the power curve of the BMW-801D2, as you can see performance decreases rapidly at high alt:

And yet another 'truth' to lay on top of so many 'truths' on this subject

http://www.warbirdsresourcegroup.org/LRG/ju390.html

Type: Long Range Bomber or Reconnaissance aircraft.
Origin: Junkers Flugzeug und Motorenwerke AG
Models: V1 to V3 and A-1
Crew: N/A
First Flight: Prototypes only
Final Delivery: None
Number Produced: V1 and V2 Only

--------------------------------------------------------------------------------
Engine:
Model: BMW 801E
Type: 18-Cylinder two-row radial
Number: Six Horsepower: 1,970 hp

--------------------------------------------------------------------------------
Dimensions:
Wing span: 165 ft. 1 in. (50.30m)
Length: 112 ft. 2.5 in. (34.20m)
Height: 22 ft. 7 in. (6.89m)
Wing Surface Area: N/A

Weights:
Empty: 81,350 lb. (36,900 kg)
Loaded: 166,448 lb. (75,500 kg)
Performance:
Maximum Speed:
Clean: 314 mph (505 kph)
With Max. Eternal Weapons: 267 mph (430 kph)
Initial Climb: N/A
Service Ceiling (Typical): N/A
Range in Recce configuration:
6,027 miles (9700 km)
Endurance in Recce configuration: 32 Hours

--------------------------------------------------------------------------------
Armament:
Eight 20mm MG 151.
Eight 13mm MG 131.

Payload:
Transport (V1): 22,046 lb. (10,000 kg)
Bomber (V3): 3,968 lb. (1800 kg)

Avionics:
FuG 200 Hohentwiel Radar.

So, once again - what are the facts? what is the truth?

Where will anybody get a clue regarding the Ju 390V1 or V2 with respect to facts.

I'm willing to believe any performance figures based on either well founded calculations based on exhaustive wind tunnel results with at least one test flight to reference areas of agreement versus differences from the theoretical.

None of those factors are present here. Period.

Now - what is YOUR source for BMW810D for the Ju 390(either V1 or V2) so that Kiwi and I shall know the 'truth'? What is your source for bomb bay existence vs wing racks?

What is the source for internal fuel of 65,000 pounds? If true, were there special mod for Recce Version to get the loiter? What was the cruise speed to attain 32 hours endurance? what was the cruise speed to get 6000-6200 miles of range? was the range an actual or a theretical? what would a flight profile and loading look like to a.) make a 32 hour Recce, b.) fly 6200 miles with a bomb load - or no bomb load? or what?

You believe a Truth but you don't have any of this to demonstrate you have an assembly of relevant facts? Nor does Kiwi.

I got involved because I saw an analysis that seemed reasonable to me based on the numbers presented. I got into this in more detail when Kiwi posed that nobody knew what they were talking about and proceeded to a.) get the math wrong by nearly 20% on his own figures and assumptions - much less any assumptions based on a referencable source that applied to the case in question.

I AM NOT an expert on the Ju 390 but I damn sure know how to plan an IFR flight plan at the outer range of my airplane's limits - you should also as well as Kiwi - but I didn't see either of you asking fundamental questions to test or demonstrate your own belief.

Now - just suppose that the BMW801 E WAS used on the Ju 390 - what are the performance figures for that? Then Soren we have one leg of the analysis that you and I could do together.

After that we need to know how much actual fuel could be loaded onto this beast and safely take off.

After that we would like to know where the best altitude and speed is for a.) minimum fuel consumption, and b.) best altitude and cruise speed for best cruise mile per gallon consumed.

Then we could figure out what mission we want - Recce with no payload, Recce with payload, Ferry with no payload, Bomb mission at max range and the payload which could be carried to max range.

If then, the payload must draw from fuel (if max fuel - max gross weight), then we have another set of condition for range.

etc, etc.

So, where do you suggest we get facts for a mission profile?

[Soren]

The V1 & V2 were equipped with the D-2 engines, the A-1 was supposedly to be equipped with the E engine.

Junkers Aircraft of WWII

Now since you're not aware of it, the E engine was no better at high alt than the D-2 engine, the extra power only giving the FW-190 A-9 a service ceiling some 200m higher than that of the D-2 powered A-8.

From German Leistung charts:
FW-190A-8, service ceiling: 10.6 km
FW-190A-9, service ceiling: 10.8 km

Wow! What an improvement!

Now if you still don't understand that the BMW-801 was the reason for the lower ceiling then I must say you've lost your touch in this area quite abit Bill.

[DerAdlerIstGelandet]

No Soren it is not

He is only asking what everyone else asks for and that is a source...

[pbfoot]

did the 390 actually fly for 32 hours or is that a should number

[Soren]

Originally Posted by DerAdlerIstGelandet

No Soren it is not

I just dislike the suspicious tone, that's all...

He is only asking what everyone else asks for and that is a source...

Which he has now recieved.

[DerAdlerIstGelandet]

Originally Posted by Soren

I just dislike the suspicious tone, that's all...

It only mirrors yours...

[Soren]

I don't recall being suspicious about anything like this.

It's a quite simple and well known fact that the BMW-801 didn't perform well at high altitude, the FW-190A suffered from this throughout its service life. So that the Ju-390, which is powered by BMW-801 engines, has a low ceiling is a no brainer really. However despite this Bill somehow comes to conclusion that the airframe was draggy

[drgondog]

Originally Posted by Soren

The V1 & V2 were equipped with the D-2 engines, the A-1 was supposedly to be equipped with the E engine.

Junkers Aircraft of WWII

Soren - two points. I found no reference to Ju 390V1 or Ju 390V2, nor BMW801D-2 engines for any version (specifically) in your link.

Second point, the link you provide references in its Technical Data table a Ju 390 (no V1, V2, A1 or A2 - just "Ju 390") with two engine configurations, namely 8x 801D or 6x 801E. Which do you prefer since only one Ju 390 was built and flown?

Below the Technical Table in your link is the last reference to the Ju 390 finally referencing a Model number - but not the V1 and V2 you referenced in your above statement.

"Ju390A1 transporter aircraft with 6 x BMW801E, one built in 1943, second not completed. "

So - what is the Model Number you propose for the Ju 390 or since only one flew and is the alleged New York Bomber shal we just refer to it as THE Ju 390?

And last - since the photos I look at seem to have only six engines and the Tables you linked to describe "6 x 801E", may we refer to 801E instead of 801D-2 from now on?

Is my request OK so far?

Now since you're not aware of it, the E engine was no better at high alt than the D-2 engine, the extra power only giving the FW-190 A-9 a service ceiling some 200m higher than that of the D-2 powered A-8.

From German Leistung charts:
FW-190A-8, service ceiling: 10.6 km
FW-190A-9, service ceiling: 10.8 km

Wow! What an improvement!


Observation - you stated earlier that the BMW 801E had well know altitude issues when I 'wondered' why a B-29, with greater WL and far less horsepower than a Ju390 - still had a service ceiling (with a 20,000 pound bomb load) 14,000+ ft higher than a Ju 390. Then you just make a statement that the 801E improved the ceiling of the Fw 190A-9 to 10.8 Km?

Question - you have a reason that an engine (BMW801E) that only increased service ceiling to 10.8 Km on an Fw 190A-9 was somehow deficient in enabling the Ju 390 to beyond 6 Km service ceiling? Where did the 801E encounter the 'high altitude' problems you alluded to at the 6Km mark?

Now if you still don't understand that the BMW-801 was the reason for the lower ceiling then I must say you've lost your touch in this area quite abit Bill.

Well, obviously you have confused me Soren. You said the BMW 801E had well known altitude problems but you point out it still enabled a higher service ceiling for the Fw 190A-9, over the service ceiling of the Fw 190A-9 with the 801D. What did I miss? Did it run into it's "well known altitude problems" with the Ju 390 at 6 Km, but somehow struggle up to 10.8Km with the Fw 190A-9.

You are an aerodynamicist, correct?

Then what is your explanation for this paradox of an alleged aircraft that has a lower wing loading, much higher base Hp with Six BMW 801E engines, but can only climb to 6 Km - when a slug of an aircraft like a B-29 with a 10% higher wing loading and 40% less power can climb to 10Km with a 20,000 pound bomb load.?

It must be clear that I have lost my touch in this area quite a bit Soren.. could you please help me find the way back to reality?

[Soren]

The FW190A-9 is a fighter for crying out loud, and its power-loading is significantly lower than that of the Ju-390, as-well wing loading, hence the higher ceiling.

Also the increased horsepower provided by the E series over the D-2 series only increased the ceiling of the FW-190 a mere 200m! Therefore there'd be no difference between a Ju-390 equipped with D-2 engines and one equipped with E series engines! Is that so hard to understand ???

Furthermore the V1 was the only one to ever fly, and it was equipped with the D-2 series engine. The A-1 was the version which was to have the E series engine, but IT NEVER FLEW!

Finally the B-29 featured four 2,200 HP turbo-supercharged engines, with excellent high alt performance, hence the higher ceiling!

If you still don't understand that the BMW-801 engines were the reason behind the Ju-390's low ceiling, then yes, you have lost your touch.

[Soren]

Perhaps we need to look at the P-47's service ceiling and compare it to the FW-190 A-9 for you to understand ?

The P-47 is turbo-supercharged fighter with a higher wing & power-loading than the FW-190A, yet it still has a higher ceiling.

Again ENGINE PEFORMANCE at altitude is the reason behind the difference in service ceiling.

[Soren]

Btw,

4 x 2,200 = 8,800 HP

6 x 1870 = 11,220 HP

That's barely a 22% difference in power.

Have no clue how you got that to be 40%.

[drgondog]

Originally Posted by Soren

Perhaps we need to look at the P-47's service ceiling and compare it to the FW-190 A-9 for you to understand ?

Perhaps you need to state what the BMW801E rated hp is for rated boost as a function of altitude to make me understand?

From Wright Pat Flight Test of P-47D-10 with P&W R2800-63 the following maximum Hp was achieved at the following

SL 2200hp@56" boost
20000 2325hp@56"
33000 2020hp@50.5
38000 1550hp@39

So, for comparable boost what are the comparable figures for the 801E?

You keep slinging insults Soren because you can't show the data to back up your statements. Stop the insults, start the facts? I can own up to being wrong but it won't be because you can not help being rude.


The P-47 is turbo-supercharged fighter with a higher wing & power-loading than the FW-190A, yet it still has a higher ceiling.

Allegedly the BMW801E is the high altitude improved version of the D-2, but all you do is talk about 'well known high altitude issues with the 801E.
I think we are still waiting to see those well know issues from a source other than your written word?

Where is the comparison you made between the Fw 190A-9, one with D-2 and one with E? Is that another 'well known' statement or do you have the facts? Facts would include Chart or Report by either LW or FW for boost, fuel type, weights as a function of altitude.

Again ENGINE PEFORMANCE at altitude is the reason behind the difference in service ceiling.

Why, yes I believe you are right, although apect ratios, power loading, wing loading are important factors?

Facts, reports, flight tests - you apparently were wrong about the BMW 801D-2 being used on the Ju 390.

You have yet to show a bomb bay for the Ju 390A1 (or V1 whichever was actually built)

You have yet to demonstrate the performance chart for the 801E in any form to use as comparison for a polite discussion on why the Ju 390 had a low service ceiling in comparison with the more heavily wing loaded B-29.

Now, I haven't seen the power charts for the R-3350-29A either. All I have for it are from Joe Baugher's website which gives 2200hp at Take Off power and 2300 at Max Power for 25,000 feet.

If you could prove that the Hp for the BMW 801E was 1800hp or less at say 15,000 feet and down to about 1200hp each at 18,000 feet we might be on our way to understanding why the Ju 390 couldn't 'get it up'.

By extrapolation however, the Fw 190A-9 with the BMW801E under those performance conditions would be sorely pressed to make 25,000ft ceiling.

This is speculation, I don't have facts on the 801E. Apparently you don't either but that doesn't stop you from drawing conclusions?

[drgondog]

Originally Posted by Soren

Btw,

4 x 2,200 = 8,800 HP

6 x 1870 = 11,220 HP

That's barely a 22% difference in power.

I was wrong on my source. I checked two others which gave 1970hp rating - but didn't specify Take Off, WEO, boost or whatever.

www.warbirdsresourcegroup.org - Luftwaffe Resource Center - Junker Ju 290

This alleges the 801E on the version of the Ju290 it was used on performed to 1970hp. I have seen as low as 1770 as high as 2300 but no other data with respect to boost, altitude, etc.

So that is 34%, not 40%, not 22%

Soren - the key fact to bring your thesis into credibility is simple - the 6 x BMW 801E must deliver less hp at 19,600 ft ceiling than the 4 R-3350-23 at 33,000 ft ceiling for the B-29A for equivalent Max Gross Take Off weights - which is where our W/L calculations rest

I Have no clue.

Now please demonstrate the 'severe power loss of the BMW801E' with facts rather than statements?

With the Ju 390 ~15% advantage in W/L for Max Gross Weight you would have to be delivering significantly less than 1500 hp at 19,600 feet to not be able to climb higher. At 1533 hp for each of the 6 engines it should be able to exceed the B-29 for rate of climb at 25,000ft based on Baugher's data.

Is that your thesis?

[Soren]

LoL, you're the one not providing any facts Bill, not me! And your ongoing accusations of me not providing any facts and your continuous suspicion is what makes me turn rude towards you, cause like most people I don't take kindly to being slapped in the face.

But show me your sources which state that the Ju-390 V1 or V2 was equipped with the BMW-801E engine. The A-1 (Which was never built, only designed) was the version meant to have the E series engine.

Anyways..

Here's the performance gain of using the BMW-801F (Superior to the 801E at all alts) over the BMW-801D-2: (From FW Leistung chart already posted Shall I post it again to easen your suspicion ?)

FW-190 A-9, Service Ceiling: 10.8 km
FW-190 A-8, Service Ceiling: 10.6 km

A whopping 200m in difference!

With the BMW-801F it takes the A-9 19.6 min to reach 10km, the poor high alt performance significantly decreasing performance above 23,000 ft.

Yeah, the BMW-801E certainly was going to help allot on high alt performance